The present invention relates to job queue management technology, and more particularly, to a method and system of job queue management in wafer fabrication.
A conventional semiconductor factory typically includes requisite fabrication tools to process semiconductor wafers for a particular purpose, employing processes such as photolithography, chemical-mechanical polishing, or chemical vapor deposition. During manufacture, the semiconductor wafer passes through a series of process steps, performed by various fabrication tools. For example, in the production of an integrated semiconductor product, the semiconductor wafer can pass through up to 600 process steps.
The wafers are typically stored in containers, such as cassettes, each of which holds up to 25 wafers. The cassettes are then loaded in carriers, such as standard mechanical interfaces (SMIFs) or front opening unified pods (FOUPs) for transport throughout the factory. A carrier may contain multiple wafer lots to undergo a fabrication task. A preparation is performed when changing process recipe. For example, an implanter must spend 10 minutes beam tuning and subsequently another 10 minutes in to implant ions upon 25 wafers. Conventionally, fabrication tools use much time repeatedly performing preparations even when wafer lots corresponding to a common recipe, are interlaced in a carrier or multiple carriers. For example, if four wafer lots, such as “lot1”, “lot2”, “lot3” and “lot4”, may require sequential implantation according to “recipe1”, “recipe2”, “recipe1” and “recipe2”, twenty minutes will be wasted performing redundant beam tunings.
In view of these limitations, a need exists for an apparatus and method of job queue management that arranges process jobs according to common recipes, thereby reducing preparation time.